1. Field of the Invention
The invention relates in general to a transmitter, a receiver and a signal extender system, and more particularly to a transmitter, a receiver and a signal extender system having a simple architecture and low cost.
2. Description of the Related Art
Transition minimized differential signaling (TMDS) is a transmission technology developed by Silicon Image, Inc. in the United States and is adapted to an image transmission interface, such as a high definition multimedia interface (HDMI) or a digital visual interface (DVI), to ensure stability of high speed serial data transmission.
Table 1 shows the transmission specifications (pin definition) of the transmission of digital video-audio signals according to the TMDS transmission technology.
TABLE 1PinPin definitionPinPin definition1TMDS Data 2+2TMDS Data 2 Shield3TMDS Data 2−4TMDS Data 1+5TMDS Data 1 Shield6TMDS Data 1−7TMDS Data 0+8TMDS Data 0 Shield9TMDS Data 0−10TMDS Clock+11TMDS Clock Shield12TMDS Clock−13CEC14Reserved15SCL16SDA17DDC/CEC Ground18+5V Power19Hot Plug Detect
Many currently available video-audio apparatuses, such as setup boxes, DVD players, personal computers and liquid crystal display televisions, adopt the TMDS transmission technology to transmit digital video-audio signals to provide high-definition image frames. However, if a more expensive transmission interface, such as HDMI or DVI, is adopted to transmit the digital video-audio signals, the cost cannot be lowered. If network cables are adopted to transmit the digital video-audio signals, 12 channels corresponding to TMDS are needed. So, two network cables, each providing eight channels, are needed to transmit the complete digital video-audio signals. Because the two network cables have different lengths, the layout becomes difficult, and the transmitted digital video-audio signals may become skewed or have undesirable signal delay, resulting in the receiver generating error signals after demodulation.
In addition, the above-mentioned problem also occurs when a transmitting device compliant with the Displayport standard transmits the low-voltage differential signal (LVDS) and the associated low frequency or single-end/low frequency signal.